1. Field of the Invention
The present invention relates to a gas purifier; in particular, to a device which provides clean gas to a wafer substrate accommodating unit.
2. Description of Related Art
Wafers are high-precision products and its storage solution demands specific conditions. For example, the gas in the storage space needs to be particle free to reduce contamination on the wafers which leads to a compromise in wafer precision. Also, the gas in the storage space cannot have water vapor or oxygen, preventing chemical reactions such as oxidation on the surface of the wafers. Therefore, replenishing the interiors of wafer accommodating units with clean gas of consistent quality is an important task in the manufacturing and transporting processes of wafers.
Publication TW M347664 discloses a prior art for solving the above problem. The disclosure includes an improved gas purifier for a Front Opening Unified Pod which fills the Front Opening Unified Pod (FOUP) with clean gas of consistent quality through the inlet of the FOUP such that the clean and consistent gas is mixed with the gas within the FOUP and then discharged through the outlet of the FOUP. As a result, the particle, oxygen and water vapor concentrations of the gas within the FOUP are significantly reduced. The disclosure also uses a tube with apertures for evenly distributing the filling within the FOUP.
However a persisting problem of the above disclosure is that when gas is not being filled into the FOUP, the gas within nonetheless flows into the tube with apertures and possibly further out of the inlet of the gas purifier, potentially contaminating the source of the clean and consistent gas.
Hence, the present inventor believes the above mentioned disadvantages can be overcome, and through devoted research combined with application of theory, finally proposes the present disclosure which has a reasonable design and effectively improves upon the above mentioned disadvantages.